Can't connect to database via RDS proxy

Hello,

I've created an Aurora Postgres database with a default proxy connected to it. But when I try to use it, it won't connect. I tried connecting with and without the signer. Here below is the code I used:

const signer = new Signer({
        /**
         * Required. The hostname of the database to connect to.
         */
        hostname: "PROXY-ENDPOINT",
        /**
         * Required. The port number the database is listening on.
         */
        port: 5432,
        /**
         * Required. The username to login as.
         */
        username: "DATABASE-USER",
        /**
         * Optional. The AWS credentials to sign requests with. Uses the default credential provider chain in not specified.
         */
        credentials: ****** (IAM admin credentials to test with)
        /**
         * Optional. The region the database is located in. Uses the region inferred from the runtime if omitted.
         */
        region: "eu-central-1",
    });
      
    const token = await signer.getAuthToken();

    console.log(token);

    const config = {
        client: "pg",
        connection: {
            timezone: "+00:00",
            host:  "PROXY-ENDPOINT",
            port: 5432,
            user: "DATABASE-USER",
            password: token,
            database: "DATABASE-NAME",
            ssl: "Amazon RDS"
        },
        pool: {
            min: 5, 
            max: 30,
            createTimeoutMillis: 30000,
            acquireTimeoutMillis: 30000,
            idleTimeoutMillis: 30000,
            reapIntervalMillis: 1000,
            createRetryIntervalMillis: 100
        },
    };

    const database = knex(config);

I use knex as database library and I used @aws-sdk/rds-signer to get the token. I've tested the code above locally and on a EC2 instance in the same VPC. Does somebody know what I did wrong?

Thanks for the help!

~Daan